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Donald Trump's campaign manager Corey Lewandowski insists his boss is leading in the polls with women and Latino voters.

Donald Trump’s campaign manager Corey Lewandowski doubled down on the candidate’s attack on New Mexico's Susana Martinez, a fellow Republican and the nation’s only Latina governor.

“We absolutely stand by our statement that the state of New Mexico could be doing better,” Lewandowski told Fox News’ Chris Wallace on Sunday, reiterating his boss’s promises to fix the state's economy by building a wall on the southern border with Mexico.

Earlier this week, Trump described New Mexico as a state with high unemployment and dependence on food stamps -- and accused Martinez of bearing the responsibility. “Your governor has got to do a better job,” he said. “She’s not doing the job. Hey, maybe I’ll run for governor of New Mexico. I’ll get this place going.”

Former House Speaker Newt Gingrich (R), who has been generally supportive of Trump’s campaign, called the comments “very, very, destructive” and said it “sent all the wrong signals.”

When asked by Wallace about the wisdom of Trump attacking Martinez, given his unpopularity among women and Latinos, Lewandowski insisted the candidate is polling well with both groups. “Donald Trump is winning with Latinos, if you look at the last poll, he’s winning with Hispanics, if you look at the polls, he’s doing very well with women,” the campaign manager said, prompting Wallace to interrupt him.

“Wait, Corey,” Wallace said. “He’s not winning with women and he’s not winning with Hispanics. His numbers are hugely underwater with both!”

Latinos favor Trump’s likely Democratic opponent, Hillary Clinton, by a 39-point margin, according to a recent Fox News Latino poll. And in a matchup between the two candidates, women favored Clinton by 51 to 38 percent in an NBC News/Wall Street Journal poll.